CN110868679B

CN110868679B - Microphone packaging structure

Info

Publication number: CN110868679B
Application number: CN201910217413.8A
Authority: CN
Inventors: 谢聪敏; 操礼齐; 李建兴; 刘志成
Original assignee: Solid State System Co Ltd
Current assignee: Solid State System Co Ltd
Priority date: 2018-08-27
Filing date: 2019-03-21
Publication date: 2022-05-03
Anticipated expiration: 2039-03-21
Also published as: US10728674B2; TW202009208A; US20200068317A1; CN110868679A; TWI735843B

Abstract

The invention discloses a microphone packaging structure, which is a microphone packaging structure of a Micro Electro Mechanical System (MEMS), and comprises a packaging substrate and an integrated circuit arranged on the packaging substrate. In addition, a MEMS microphone is disposed on the package substrate, wherein the MEMS microphone is electrically connected to the integrated circuit. The conductive adhesive layer is arranged on the packaging substrate and surrounds the integrated circuit and the MEMS microphone. The bottom of the cap structure is adhered to the conductive adhesive layer. The underfill layer is disposed on the package substrate and covers the outer side of the conductive adhesive layer.

Description

Microphone packaging structure

Technical Field

The invention relates to a Micro Electro Mechanical System (MEMS) microphone packaging technology.

Background

Microphones are designed based on semiconductor manufacturing techniques in order to reduce the size considerably. MEMS microphones are a common component for electronic devices to sense acoustic signals, such as, for example, communication speech.

After the MEMS microphone is fabricated on a wafer and diced into multiple dies, the MEMS microphone in a single die is connected to an integrated circuit, such as an application-specific integrated circuit (ASIC), for example, by a packaging fabrication process.

In order to properly protect the microphone connected to the ASIC, a metal cap is typically used to cover the MEMS microphone during the package manufacturing process. In the past, metal caps were disposed on package substrates by titanium nitride solder paste to ground the metal caps.

Since titanium nitride solder paste may splash at high temperatures, the sputtered titanium nitride solder paste may contaminate the ASIC and/or MEMS microphone. MEMS microphone packages may suffer from defects that result in reduced performance.

Disclosure of Invention

The present invention provides a microphone package structure in which a metal cap is disposed over a package substrate to avoid contamination at a MEMS microphone and/or ASIC.

The invention provides a MEMS microphone packaging structure which comprises a packaging substrate and an integrated circuit arranged on the packaging substrate. In addition, a MEMS microphone is disposed on the package substrate, wherein the MEMS microphone is electrically connected to the integrated circuit. The conductive adhesive layer is arranged on the packaging substrate and surrounds the integrated circuit and the MEMS microphone. The bottom of the cap structure is adhered to the conductive adhesive layer. The underfill layer is disposed on the package substrate and covers the outer side of the conductive adhesive layer.

The invention provides a MEMS microphone packaging structure which comprises a packaging substrate and an integrated circuit arranged on the packaging substrate. In addition, a MEMS microphone is disposed on the package substrate, wherein the MEMS microphone is electrically connected to the integrated circuit. A plurality of conductive adhesive layers are disposed on the package substrate and surround the integrated circuit and the MEMS microphone. The bottom of the cap structure is adhered to the plurality of conductive adhesion layers. An underfill layer is disposed on the package substrate surrounding the integrated circuit and the MEMS microphone, wherein each sidewall of the plurality of conductive adhesive layers and a gap between the cap structure and the package substrate are sealed by the underfill layer.

A MEMS microphone package structure includes a package substrate and an integrated circuit disposed on the package substrate. In addition, a MEMS microphone is disposed on the package substrate, wherein the MEMS microphone is electrically connected to the integrated circuit. The conductive adhesive layer is arranged on the packaging substrate and surrounds the integrated circuit and the MEMS microphone. The cap structure disposed on the package substrate includes a top plate, a wall, a bottom horizontal portion, and a cover portion. The legs of the wall are located on the package substrate and surround the integrated circuit and the MEMS microphone, with the top plate disposed vertically on the wall. The bottom horizontal portion is vertically disposed on the package substrate between the wall and the conductive adhesive layer. The covering part is arranged on the conductive adhesion layer and is jointed with the bottom horizontal part.

In order to make the aforementioned and other features and advantages of the invention more comprehensible, embodiments accompanied with figures are described in detail below.

Drawings

FIG. 1 is a cross-sectional view of a MEMS microphone package with a sputtering effect according to an embodiment of the present invention;

FIG. 2 is a cross-sectional view of a MEMS microphone package with a sputtering effect according to an embodiment of the present invention;

FIG. 3 is a cross-sectional view of a MEMS microphone package without the splash tin effect according to an embodiment of the present invention;

FIG. 4 is a cross-sectional view of a MEMS microphone package without the splash tin effect according to an embodiment of the present invention;

FIGS. 5A-5F are schematic diagrams illustrating a cross-sectional structure of a MEMS microphone package manufacturing process according to an embodiment of the present invention;

FIGS. 6A-6F are schematic diagrams illustrating a cross-sectional structure of a MEMS microphone package manufacturing process according to an embodiment of the present invention;

FIG. 7 is a schematic top view of a conductive epoxy layer and an underfill layer according to one embodiment of the present invention;

FIG. 8 is a schematic top view of a conductive epoxy layer and an underfill layer according to one embodiment of the present invention;

FIG. 9 is a schematic diagram showing the cross-sectional structure of the MEMS microphone package of FIG. 8 along the tangent line I-I according to one embodiment of the present invention;

FIG. 10 is a schematic diagram showing the cross-sectional structure of the MEMS microphone package of FIG. 8 along line II-II of the MEMS microphone package according to one embodiment of the present invention;

FIGS. 11A-11F are schematic diagrams illustrating a top view structure of a MEMS microphone package manufacturing process according to an embodiment of the present invention;

FIG. 12 is a cross-sectional view of a MEMS microphone package without the splash tin effect according to an embodiment of the present invention;

fig. 13A to 13E are schematic diagrams illustrating a cross-sectional structure of a MEMS microphone package manufacturing process according to an embodiment of the invention.

Description of the symbols

100: package substrate

102: connecting pad

104: MEMS microphone

104 a: semiconductor substrate

104 b: dielectric layer

104 c: back plate

104 d: aperture

104 e: reaction chamber

105: adhesive material

106: integrated circuit with a plurality of transistors

108: solder paste layer

110. 220, and (2) a step of: cap structure

112. 124: sound hole

120: wall(s)

122: top board

150: cutting path

200: underfill layer

202: injection device

208: conductive adhesive layer

210: cutting manufacturing process

220 a: region(s)

I-I, II-II: tangent line

Detailed Description

The invention relates to MEMS microphone packaging, wherein the tin splashing effect can be effectively reduced.

Various embodiments are provided to illustrate the present invention, however, the present invention is not limited to these embodiments. In addition, the various embodiments provided may be combined with each other as other embodiments.

Fig. 1 is a schematic diagram illustrating a cross-sectional structure of a MEMS microphone package with a tin sputtering effect according to an embodiment of the invention. Referring to fig. 1, the present invention at least investigated MEMS microphone packages and found the effect of tin sputtering. The spattering of tin occurs as follows.

After the MEMS microphone 104 and the integrated circuit 106 are fabricated, they are packaged together on a package substrate 100, such as a Printed Circuit Board (PCB) substrate, for example. The package substrate 100 has a circuit trace with connection pads 102 for electrically connecting between the MEMS microphone 104 and the integrated circuit 106. However, the invention is not limited thereto. In another embodiment, well-known bond wires may also be used.

The integrated circuit may be, for example, an ASIC die. The basic structure of the MEMS microphone 104 includes a semiconductor substrate 104a with a reaction chamber 104 e. The dielectric layer 104b is used to support internal structures disposed on the semiconductor substrate 104 a. The backplate 104c is supported by the dielectric layer 104b, wherein the backplate 104c has vent holes for receiving sound from the sound holes 112 of the cap structure 110. The diaphragm 104d supported by the dielectric layer 104b vibrates in response to air vibration caused by an acoustic signal. The capacitance variation between the back plate 104c and the diaphragm 104d is detected and converted into a voice frequency in the form of an electrical signal.

The cap structure 110 is typically a metal cap that covers the MEMS microphone 104 and the integrated circuit 106 for protection purposes. The cap structure 110, such as a metal cap, for example, may also be grounded to further shield noise, wherein the cap structure 110 is connected to the package substrate 100 by a solder paste layer 108, and the solder paste layer 108 is typically titanium nitride solder paste.

As described herein, when the solder paste layer 108 melts to adhere the metal cap structure 110 to the package substrate 100, the solder paste material may splash at high operating temperatures. The sputtered solder paste may enter the MEMS microphone 104 and/or the integrated circuit 106, contaminating the components. The efficiency of the MEMS microphone package may be reduced or even destroyed.

Fig. 2 is a schematic diagram illustrating a cross-sectional structure of a MEMS microphone package with a tin sputtering effect according to an embodiment of the invention. The MEMS microphone package is not limited to the structure of fig. 1. Referring to fig. 2, which is an example of a MEMS microphone package with a different structure, the sound hole 124 may be formed in the package substrate 100. Further, the capping structure in this example may be formed of multiple parts including the solder paste layer 108, the wall 120, another solder paste layer 108, and the top plate 122, which are stacked to form the capping structure. However, in such MEMS microphone packages, the effect of tin splashing still occurs.

In order to reduce or eliminate the effect of the spattering of tin, the invention further provides other MEMS microphone packages. In an embodiment of the structure shown in fig. 1, fig. 3 is a schematic diagram illustrating a cross-sectional structure of a MEMS microphone package without the effect of splashing tin according to an embodiment of the invention.

Referring to fig. 3, according to the structure of fig. 1, the present invention uses a conductive adhesive layer 208, such as a conductive epoxy layer, instead of the solder paste layer 108 of fig. 1. The conductive adhesive layer 208 does not cause the effect of sputtering tin. However, the conductive adhesive layer 208 after the curing process may have some cracks existing in the conductive adhesive layer 208. The present invention uses an underfill layer 200 to cover the outside of the conductive adhesive layer 208. The underfill layer 200 may enter and fill the cracks.

Fig. 4 is a schematic diagram showing a cross-sectional structure of a MEMS microphone package without a tin sputtering effect according to an embodiment of the invention. Referring to fig. 4, according to the MEMS microphone package structure of fig. 2, the conductive adhesive layer 208 is used to replace the solder paste layer 108, and the underfill layer 200 also covers the conductive adhesive layer 208, wherein a small portion of the underfill layer 200 can enter and fill cracks that may occur in the conductive adhesive layer 208 after the curing process. Therefore, in this embodiment, the effect of the spattering of tin can be effectively eliminated.

The packaging method for packaging the MEMS microphone is shown in fig. 3 and 4. Fig. 5A to 5F are schematic diagrams illustrating cross-sectional structures of a MEMS microphone package manufacturing process according to an embodiment of the invention.

Referring to fig. 5A, a package substrate 100, such as a PCB substrate, is provided. The connection pads 102 are formed in the package substrate 100. Referring to fig. 5B, the integrated circuit 106 and the MEMS microphone 104 are disposed on the package substrate 100 through the adhesive material 105. The integrated circuit 106 and the MEMS microphone 104 are connected in the package substrate 100 via circuit routes or via conventional bond wires (not shown). The invention is not limited to this embodiment.

Referring to fig. 5C, a conductive adhesive layer 208, such as a conductive epoxy material, is disposed on the bonding pads 102 of the package substrate. In one embodiment, the conductive adhesive layer 208 surrounds the MEMS microphone 104 and the integrated circuit 106.

Referring to fig. 5D, the cap structure 110 is disposed on the conductive adhesive layer 208. In other words, the cap structure 110 is disposed over the package substrate 100 through the conductive adhesive layer 208, and the conductive adhesive layer 208 is disposed on the connection pads 102, surrounding the MEMS microphone 104 and the integrated circuit 106. In one embodiment, the cap structure 110 is a metal cap, which may have acoustic holes. At this stage, a curing process, such as a baking process, is performed on the conductive adhesive layer 208 to cure the conductive adhesive layer 208.

Referring to fig. 5E, underfill layer material is injected from the injection apparatus 202 to the outside of the conductive adhesive layer 208 and the bottom of the cap structure 110. Therefore, the underfill layer 200 is formed on the package substrate 100 to cover the conductive adhesive layer 208, wherein the liquid portion of the underfill layer material can enter and fill cracks that may appear in the conductive adhesive layer 208 after the curing process.

Referring to fig. 5F, a dicing process 210 is performed along dicing streets remaining on the package substrate 100 to package a plurality of MEMS microphones.

As observed in MEMS microphone packages, the effect of tin sputtering can be effectively eliminated.

To fabricate a MEMS microphone package as shown in fig. 4, further embodiments are provided. Fig. 6A to 6F are schematic diagrams illustrating cross-sectional structures of a MEMS microphone package manufacturing process according to an embodiment of the invention.

Referring to fig. 6A, a package substrate 100 is provided. In this embodiment, the acoustic hole 124 is formed in the package substrate 100. Referring to fig. 6B, the wall 120 is disposed on the conductive adhesive layer 208, surrounding the integrated circuit 106 and the MEMS microphone 104. Referring to fig. 6C, a top conductive adhesive layer 208 is formed on the top of the wall 120. The top plate 122 is disposed on the top conductive adhesive layer 208.

Referring to fig. 6D, a portion of the two conductive adhesive layers 208 and the wall 120 are removed to expose the package substrate 100 and create a gap between two adjacent MEMS microphone packages. Referring to fig. 6E, after the curing process, an underfill layer 200 is injected on the conductive adhesive layer 208 to fill the gap between two adjacent MEMS microphone packages. The underfill layer 200 covers the two conductive adhesive layers 208 and fills the seams that may be present in the conductive adhesive layers 208.

Referring to fig. 6F, the MEMS microphone package is separated by cutting the scribe line remained on the package substrate 100.

FIG. 7 is a schematic top view illustrating the relationship between a conductive epoxy layer and an underfill layer according to one embodiment of the invention. Referring to fig. 7, the relative position between the conductive adhesive layer 208 and the underfill layer 200 is shown according to the top view of the MEMS microphone package of fig. 3, the underfill layer 200 is between the package substrate 100 and the outer side of the conductive adhesive layer 208, and the cap structure 110 (not shown in fig. 7) is disposed on the conductive adhesive layer 208. In one embodiment, the conductive adhesive layer 208 surrounds the MEMS microphone 104 and the integrated circuit 106.

FIG. 8 is a schematic top view illustrating the relationship between a conductive epoxy layer and an underfill layer according to one embodiment of the invention. Fig. 9 is a schematic diagram showing a cross-sectional structure of the MEMS microphone package of fig. 8 along a tangent line I-I according to an embodiment of the invention. Fig. 10 is a schematic diagram showing a cross-sectional structure along a tangent line II-II of the MEMS microphone package in fig. 8 according to an embodiment of the invention.

Referring to fig. 8 in accordance with fig. 9 or fig. 10, a plurality of conductive adhesive layers 208 are disposed on the package substrate 100, surrounding the MEMS microphone 104 and the integrated circuit 106.

In one embodiment, the conductive adhesive layer 208 may be a solder paste layer, but the invention is not limited thereto. In one embodiment, the conductive adhesive layer 208 does not continuously surround the MEMS microphone 104 and the integrated circuit 106. In this manner, there are gaps between the conductive adhesive layers 208 as shown in fig. 8.

In this embodiment, when the cap structure 110 is disposed on the conductive adhesive layer 208, as shown at the tangent line I-I in fig. 9, there is a gap between the cap structure 110 and the package substrate 100, but the conductive adhesive layer 208 is provided with a gap in the form of a conductive adhesive separation region. Further along the tangent line II-II as shown in fig. 10. There is also a gap between the cap structure 110 and the package substrate 100, but space is maintained available before the underfill layer 200 is formed. The gap in the available space allows the underfill layer material to infuse and extend into the inboard region. Thus, the underfill layer 200 covers the outside and inside of the conductive adhesive layer 208. As mentioned above, in one embodiment, the conductive adhesive layer 208 may be solder paste, but the invention is not limited thereto.

In order to manufacture the MEMS microphone package of fig. 8 to 10, the package manufacturing process is improved. Fig. 11A to 11F are schematic diagrams illustrating a top view structure of a MEMS microphone package manufacturing process according to an embodiment of the invention.

Referring to fig. 11A, a package substrate 100 is provided. For a singulation process (singulation process), the package substrate 100 has scribe lines 150 left thereon. In one embodiment, the connection pads 102 distributed on the package substrate 100 surround the reserved area. In one embodiment, the plurality of connection pads 102 are not continuous.

Referring to fig. 11B, the MEMS microphone 104 and the integrated circuit 106 are disposed in a reserved area on the package substrate 100 and are discontinuously surrounded by the connection pads 102.

Referring to fig. 11C, a plurality of conductive adhesive layers 208, such as solder paste, are disposed on the plurality of connection pads 102, wherein the conductive adhesive layers 208 are formed as discrete conductive adhesive separation regions. Referring to fig. 11D, a cap structure 110, such as a metal cap, is disposed on the conductive adhesive layers 208 by reflow process with solder paste.

Referring to fig. 11E, an underfill material is injected into the package substrate 100 to form an underfill layer 200. Due to the gap between the cap structure 110 and the package substrate 100, the underfill material of the underfill layer 200 may flow through the gap and cover the inner side of the conductive adhesive layer 208. Referring to fig. 11F, the package substrate 100 is cut along the scribe line 150 (as shown in fig. 11A) to form a plurality of MEMS microphone packages.

In other embodiments, the effect of splashing tin can be reduced while using conventional tin paste. Fig. 12 is a schematic diagram showing a cross-sectional structure of a MEMS microphone package without a tin sputtering effect according to an embodiment of the invention.

Referring to fig. 12, with reference to the structure of fig. 1, it is suggested that the cap structure 220 be modified as the region 220 a. Conventional solder paste may be used to form the solder paste layer 108. Only the details of the cap structure 220 are described here, and the details of the other parts are not repeated.

A cap structure 220, such as a metal cap, for example, is disposed on the package substrate 100. Generally, the cap structure 220 includes a top plate, walls, a bottom horizontal portion, and a covering portion. The legs of the wall are located on the package substrate 100 and surround the integrated circuit 106 and the MEMS microphone 104, with the top plate vertically disposed on the wall; the bottom level portion is disposed on the package substrate 100 between the legs of the walls and the solder paste layer 108; the cover portion is disposed on the solder paste layer 108 and connected to the bottom horizontal portion. As described above, the solder paste layer 108 is described as an example. In another embodiment, the solder paste layer 108 can also be a conductive adhesive layer in general.

Similar to the cross-sectional view of area 220a, the solder paste layer 108 may be isolated during the step. The solder paste layer 108 at the temperature of the reflow process will not splatter to the integrated circuit 106 and/or the MEMS microphone 104.

With respect to the packaging method, fig. 13A to 13E are schematic diagrams illustrating the cross-sectional structure of the MEMS microphone package manufacturing process according to an embodiment of the invention.

Referring to fig. 13A, a package substrate 100 having connection pads 102A is provided. Referring to fig. 13B, the integrated circuit 106 and the MEMS microphone 104 are disposed on the package substrate 100 through the adhesive material 105. The integrated circuit 106 and the MEMS microphone 104 are connected in the package substrate 100 via circuit routes or via conventional bond wires (not shown). However, the invention is not limited thereto.

Referring to fig. 13C, a solder paste layer 108, such as tin-titanium-nitride (tin-tin) paste, is disposed on the bonding pads 102 of the package substrate 100. In an embodiment, the solder paste layer 108 surrounds the MEMS microphone 104 and the integrated circuit 106.

Referring to fig. 13D, a cap structure 110 is disposed on the solder paste layer 108. In other words, the cap structure 110 is disposed over the package substrate 100 via the solder paste layer 108, which is disposed on the connection pads 102, surrounding the MEMS microphone 104 and the integrated circuit 106. In one embodiment, the cap structure 220 is a metal cap, which may have acoustic holes. At this stage, a curing process, such as a baking process, is performed on the solder paste layer 108 to cure the solder paste layer 108.

Notably, the cap structure 220 has a bottom region 220a that is structured as described above to isolate the solder paste layer 108. In such an environment, the spattering tin effect will not occur to the MEMS microphone 104 and the integrated circuit 106.

Referring to fig. 13E, the package substrate 100 may be cut along the cutting lines by a cutting process 210 to have a plurality of MEMS microphone packages.

The present invention has at least investigated MEMS microphone packaging and found that the tin splash effect will not be present in the MEMS microphone 104 and/or the integrated circuit 106. The present invention provides embodiments whose tin spattering effect can be effectively reduced or even eliminated.

Although the present invention has been described with reference to the above embodiments, it should be understood that the invention is not limited thereto, and that various changes and modifications can be made by those skilled in the art without departing from the spirit and scope of the invention.

Claims

1. A MEMS microphone package structure, comprising:

a package substrate;

an integrated circuit disposed on the package substrate;

the micro-electro-mechanical system microphone is arranged on the packaging substrate, and is electrically connected with the integrated circuit;

a conductive adhesive layer disposed on the package substrate surrounding the integrated circuit and the MEMS microphone; and

a cap structure disposed on the package substrate, wherein the cap structure comprises:

a top plate;

a wall with a foot end on and contacting the package base and surrounding the integrated circuit and the mems microphone, wherein the top plate is vertically disposed on the wall;

a bottom horizontal portion vertically disposed in contact with the package substrate between the foot end of the wall and the conductive adhesive layer, and located outside and in contact with the foot end of the wall, wherein the conductive adhesive layer is further outside the bottom horizontal portion and in contact with the bottom horizontal portion; and

a cover disposed on the conductive adhesive layer and bonded to the bottom horizontal portion, the conductive adhesive layer being between the cover and the package substrate.

2. The mems microphone package structure of claim 1, wherein the integrated circuit is coupled to the mems microphone via the package substrate.

3. The mems microphone package structure of claim 1, the package substrate being a printed circuit board substrate.

4. The mems microphone package structure of claim 1, wherein the package substrate includes a connection pad surrounding the integrated circuit and the mems microphone, and the conductive adhesive layer is disposed on the connection pad.

5. The mems microphone package structure of claim 1, wherein the cap structure is a metal cap.

6. The mems microphone package structure of claim 5, wherein the metal cap has an acoustic aperture to receive an acoustic signal.

7. The mems microphone package structure of claim 1, wherein the conductive adhesive layer is a solder paste layer.